Many micro-electromechanical systems (MEMS) require a power source of electrical energy. In some instances electrical power is provided by a coupled battery or battery system. The size advantage of the MEMS device is lost if the battery is large. Physical limitations of the electrode materials, separators, and electrolyte dictate their separate manufacture, and subsequent coupling of the battery to the MEMS device.
MEMS technology also has enabled development of fully implantable medical devices. The power supplies for these devices, however, can account for up to 85% of the mass and 35% of the volume of these systems. The smallest commercially available batteries are in the millimeter (mm) range and utilize zinc or lithium chemistries. Stainless steel casing is typically used to contain the fluid electrolyte and the gaseous reaction byproducts.
Further miniaturization of implantable systems requires new battery technologies with enhanced compatibility with MEMS fabrication techniques and with MEMS-processing compatible materials and substrates. Power source selection will also rely on more than the electrochemistry. Form factor, performance, lifetime, toxicity of the chemistry and the rate of heat generation must be considered in the design process. This is particularly true with implantable systems.